To measure and compare the Canon 17-55mm's purple fringing caused by lens chromatic aberrations and sensor
blooming, we photographed a test chart with areas of very high contrast
using it and a number of rival lenses.

We tested each lens at its
widest and longest focal lengths with the aperture wide open. The crops are taken from the upper left
corner of the chart and presented here at 100%.

The Canon EF-S 17-55mm exhibits a little purple fringing
at its widest position in line with the others. Fringing is virtually absent
at the long end, again in line with the other three.

Canon EF-S 17-55mm f/2.8 IS USM

Canon EF-S 17-85mm f/4-5.6 IS USM

Canon EF-S 18-55mm f/3.5-5.6

Canon EF 17-40mm f/4.0L USM

17-55mm EF-S at 17mm f2.8

17-85mm EF-S at 17mm f4.0

18-55mm EF-S at 18mm f3.5

17-40mm EF L at 17mm f4

17-55mm EF-S at 55mm f2.8

17-85mm EF-S at 85mm f5.6

18-55mm EF-S at 55mm f5.6

17-40mm EF L at 40mm f4

Canon EF-S 17-55mm f/2.8 IS USM macro comparison

17-55mm EF-S at 55mm f8
Max area of 124x82mm

To measure and compare the Canon 17-55mm's macro performance we photographed
a chart using it and a number of rival lenses at a focal length and distance which
delivered the maximum possible reproduction.

The dark lines are 10mm apart and the result is not cropped. Smaller areas
are preferred in this test.

The image left was taken with the Canon 17-55mm zoomed-into 55mm where it captured an area measuring 124x82mm. This is a larger area than the other three lenses on test, and proves there's better choices if macro's your thing.